Faceted single-crystalline ZnO tubes were synthesized by a simple soft solution method at 65 degrees C. These tubes are of several micrometers in length and several hundred nanometers in diameter, with bell-mouths on each end. Structural characterizations using electron spectroscopy revealed that these hexagonal ZnO tubes were along [0001] direction and side-enclosed by {01 (1) over bar0} facets. The growth of ZnO in hydrothermal condition and the formation of this unusual bell-mouthed structure were discussed on the basis of the observation of ring-shaped nanocrystallites upon decreasing the time for growth. (c) 2005 Elsevier B.V. All rights reserved.